Stuck throttle safety device

ABSTRACT

An internal combustion engine, associated with a vehicle, has a carburetor with a throttle valve which upon being opened a predetermined degree closes a related first electrical switch; a second electrical switch is closed in response to the vehicular main power transmission being placed in some mode of power transmission therethrough, a third electrical switch is closed in response to the actuation of the vehicle brake pedal; when the above switches are closed a resulting relay operated switch is energized thereby opening the circuit leading from a source of electrical potential to the related vehicle ignition system so as to thereby prevent the occurrence of a spark discharge at the engine igniter or spark plug assemblies thereby shutting down the engine.

United States Patent 1 1 3,620,324

[72] Inventor Marlon L.Sm1tley 2,740,947 4/1956 Davies 340/52 127 N lnali lns nwoodslvllch. 2,895,561 7/1959 McCollough.. 180/103 48070 2,960,174 11/1960 Walker 180/103 [21] AppLNo. 888,679 3,273,552 9/1966 Plath 340/53X [22] Filed Dec.29, 1969 Primary Examiner-Kenneth l-l. Betts [45] Patented 1971 An0rney-Walter Potoroka, Sr.

[54] STUCK THROTTLE SAFETY DEVICE ABSTRACT: An Internal combustion englne, associated with 14 Claims, 7 Drawing Figs.

a vehicle, has a carburetor w1th a throttle valve which upon [52] LS-Cl 180/103, being opened a predetermined degree closes a related first 23/198130 192/4A electrical switch; a second electrical switch is closed in [51] lnt.Cl. ..B60k 27/08 response to the vehicular i Power transmission being [50] Field of Search 180/82, placed in some mode f power f fi i therethl-ough, a 103; 340/52, 53; 123/198 DC. 198 D, 198 R, 108; third electrical switch is closed in response to the actuation of 92/4 3 the vehicle brake pedal; when the above switches are closed a resulting relay operated switch is energized thereby opening [56] Rem-em cued the circuit leading from a source of electrical potential to the UNITED STATES PATENTS related vehicle ignition system so as to thereby prevent the oc- 2,337,838 12/1943 Reavis 123/198 currence of a spark discharge at the engine igniter or spark 2,509,400 5/1950 Roswell 180/103 plug assemblies thereby shutting down the engine.

PAIENTElluuv 16 I97! 3,620 324 sum 1 or 2 J j flambzz a9. W W g,

ATTORNEY STUCK THROTTLE SAFETY DEVICE BACKGROUND OF THE INVENTION It has been found that on occasion a vehicle has been involved in an accident because of having the throttle valve within, for example, the carburetor induction passage become stuck in an opened position. Such throttle sticking may have been the result of a floor mat within the vehicle passenger compartment interferring with the throttle foot pedal, bent or damaged throttle control linkages or malfunctioning of the related or associated components.

Accordingly, the invention as herein disclosed and described is directly concerned with the solution of the above as well as other related problems so as to prevent the occurrence of an accident resulting from having a throttle valve become stuck in an opened position.

SUMMARY OF THE INVENTION According to the invention, a safety device for a vehicle having an internal combustion engine with air induction passage means provided with a variably openable throttle valve within said induction passage means for variably controlling the admission of combustion air to said engine in accordance with the degree of opening of said throttle valve, said safety device comprising a source of electrical potential, a first switch means closed in response to the movement of a vehicular brake pedal in the brake-applying direction, a second switch means closed in response to the placement of a main power transmission assembly of said vehicle into a condition for transmitting power from said engine to associated drive wheels of said vehicle, third switch means closed in response to said throttle valve being opened a predetermined degree, and electrical conductor means placing said source of electrical potential and said first, second and third switch means in circuit, and said first, second and third switch means being effective upon being collectively electrically closed to prevent the occurrence of a spark discharge in a spark plug of said engine.

Various objects and advantages of the invention will become apparent when reference is made to the following detailed description considered in conjunction with the accompanying drawings.

DESCRIPTION OF THE DRAWINGS In the drawings, wherein certain details may be omitted from one or more views for purposes of clarity:

FIG. 1 fragmentarily illustrates, in elevation, a carburetor for an internal combustion engine along with a schematically illustrated wiring diagram embodying a safety device constructed in accordance with the teachings of the invention;

FIG. 2 is an enlarged fragmentary view, partly in cross section, taken generally on the plane of line 22 of FIG. I and looking in the direction of the arrows;

FIG. 3 is a fragmentary cross-sectional view taken generally on the plane of line 33 of FIG. 2 and looking in the direction of the arrows; I

FIG. 4 is a fragmentary view illustrating a second embodiment of the invention as shown in FIG. 1;

FIG. 5 is a schematic wiring diagram illustrating a third embodiment of the invention;

FIG. 6 is a schematic wiring diagram illustrating a fourth embodiment of the invention; and

FIG. 7 is a schematic wiring diagram illustrating a fifth embodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now in greater detail to the drawings, FIG. 1 fragmentarily illustrates, in elevation, a carburetor 10 and associated circuitry constructed in accordance with the teachings of this invention. The carburetor 10 is illustrated as being comprised of a main body 12 having an induction passage 14 formed therethrough with a throttle valve 16 therein controlling the discharge of combustible mixtures into the engine intake manifold 18. As is shown, the throttle valve 16 is mounted on a tranversely extending throttle shaft 20 which has its one end 22 fixedly secured to a throttle actuating lever 24 which may have its lower end pivotally connected to an end 26 of suitable linkage 28 leading as to the conventional foot-operated throttle lever 30.

A rotatable choke shaft 32 extending generally transversely of the carburetor body 12 carries a choke valve (not shown but well known in the art) situated generally within the upper portion 34 of the carburetor so as to control the flow of air into the upper inlet end of the induction passage 14. As shown, a choke lever 36 is fixedly secured to choke shaft 32 for rotation therewith. Although not shown, since the invention is not dependent thereon, the position of the choke valve may be determined by any suitable manual or automatic means each of which is well known in the art.

The other end of choke lever 36 is pivotally connected to an end 38 of a fast-idle cam control linkage 40 to the other end 42 of which is suitable slideably received and retained within an arcuate slot 44 formed in the fast-idle cam member 46. The body 48 of cam member 46 is generally eccentrically disposed with respect to and pivotally carried by a suitable pivot member 50 secured to the carburetor body 12. The eccentrically disposed peripheral edge of the cam body 48 is formed to provide a plurality of discrete stepped surfaces 52, 54, 56, 58 and 60 which are generally selectively positioned in the path of travel of cooperating throttle valve stop screw 62. That is, as is generally well known, fast idle cam members are provided so as to permit the throttle valve, during curb-idle operating conditions, to remain open to a greater extent when the engine is cold and to progressively reduce the extent of additional opening in accordance with the increase of engine temperature.

Therefore, one way of accomplishing this is to connect the choke valve to the fast idle cam 46 and to thereby position the fast idle cam in accordance with choke valve position which, in turn, is reflective of engine temperature.

FIG. 1 assumes a cold engine condition and accordingly the choke valve therein would be nominally closed causing the choke lever 36 to have been rotated clockwise to the position illustrated and thereby, through connecting linkage 40, raise the fast idle cam member 46 to the position shown presenting the most eccentrically disposed stepped surface 52 in the normal path of travel of throttle lever stop screw 62.

As shown, the threaded shank portion 64 of screw 62 is threadably engaged with a laterally extending portion 66 of throttle lever 24 so as to be generally swung therewith upon rotation of the throttle lever 24 and throttle shaft 20. When the throttle lever 24 is released permitting it to be rotated toward its nominally closed position by the return spring 68, lever 24 and throttle shaft 20 will rotate counterclockwise about the centerline of shaft 20 until such time as when end 70 of abutment screw 62 abutably engages one of the stepped surfaces which, in the case illustrated, would be the maximum step 52. A coiled compression spring 72 is preferably provided about screw shank 64 and between the lever arm portion 66 and head 74 of screw 62 in order to apply a frictional holding force preventing the unintentional movement of screw 62 with respect to arm portion 66.

In the associated circuitry, a suitable source of electrical potential 76 having a first terminal 78 connected to ground as at 80, has its other terminal 82 connected to a fixed contact 84 as by a conductor 86. A normally open moveable switch contact member 88 is electrically connected to a conductor 90 leading to a second fixed electrical contact 92 which cooperates with a second normally open switch member 94. An electrical conductor 96, having one end connected to a first terminal of an electrically energizeably indicator or warning bulb or lamp 98, has its other end connected to conductor 90 as at 100. The other terminal of warning lamp 98 is connected to ground potential as by a conductor I02. The second switch member 94 is electrically connected to one end of a conductor 104 which has its opposite end 106 connected to a moveable switch contact 108 of a switch assembly 110 fixedly carried by the carburetor body 12.

As shown, the first moveable switch member 88 is operatively connected to the vehicular brake actuating foot pedal 112 so that actuation of the pedal 112 causes closure of the moveable switch member 88 thereby closing the circuit between conductors 86 and 90 and energizing the warning lamp 98 (which may actually be the conventional brake or stop light mounted at the rear of the associated vehicle).

The second moveable switch member 94 is shown as being operatively connected to a selector lever 114 and/or usual transmission selector switch assembly with a vehicular transmission assembly 1 17. In a vehicle having an automatic transmission assembly, the selector lever 1 14 usually may be placed in any of a plurality of selected positions each of which determines a particular mode or range of transmission operation. Such selected positions are usually referred to as, Park, Reverse, Neutral, Forward or Drive and Low. Such positions are respectively pictorially depicted at P,R,N,D and L in FIG. 1. The operative connection between the selector or shift lever 1 14, or the transmission housed selector switch, and the moveable contact 94 is such as to cause contact 94 to be closed against the fixed contact 92 thereby completing the circuit from conductor 90 to conductor 104.

An ignition switch assembly 116 has the terminal of a moveable switch member 118 connected to a fixed contact 120 as by a conductor 122 while the fixed contact 124 of assembly 116 is connected to terminal 82 as by a conductor 126.

A relay assembly 128 is comprised generally of a moveable switch contact member 130 operatively connected to a move able core 132 about which is formed an actuating coil 134 having its terminals 136 and 138 respectively connected to conductors 140 and 142 leading to ground potential, as at 80, and the carburetor mounted switch assembly 110. As illustrated, contact member 130 is held normally closed against fixed contacts 120 and 146 with contact 146 being electrically connected to a terminal 148 of the primary induction coil or winding 150 of a conventional ignition system coil assembly 152 which, as is well known, includes a secondary winding 154. The other terminal 156 of primary winding 150 is electrically connected to a conductor 158 which has its opposite end connected to a first contact 160 of a breaker type of contact assembly 162 such as that commonly included within a conventional engine ignition distributor assembly. The contact assembly 162 also includes a second electrical contact 164 which is connected to a conductor 166 having its other end going to ground as at 80. As is accepted practice in ignition systems employing a breaker contact assembly, a condenser 168 may be connected to conductors 166 and 158 so as to be in parallel with the breaker contact assembly 162.

A first terminal 170 of the secondary winding 154 is connected to ground 80, as by a conductor 172, while the second terminal 174 is connected to a rotatable spark-distributing arm 176 of an ignition distributor assembly 178 which, as illustrated may have a plurality of fixed electrical terminals 180, 182, 184 and 186 is electrically connected to a spark plug or igniter assembly 188 carried by the internal combustion engine for igniting the combustible mixtures within the engine cylinders in timed relationship to the engine crankshaft rotation. Ofcourse, as is well known in the art, the breaker contact assembly 162 and the condenser 168 may actually be contained within the housing of distributor assembly 178. Accordingly, as the engine crankshaft is rotated, the contacts 164 and 160 would be sequentially closed and opened so as to induce a high voltage into the secondary winding 154. Also, as the crankshaft rotates the arm 176 is also rotated causing it to be sequentially juxtaposed to the terminals 180, 182, 184 and 186. When so juxtaposed, the secondary winding 154 causes the related spark plug assembly to fire thereby igniting the combustible mixture and driving the associated piston within the engine.

As shown in each of FIGS. 1, 2 and 3, the switch assembly 1 10 is illustrated as being comprised of an electrically nonconductive base portion 190, secured to the body 12 as by screw means 192, and an integrally formed moveable arm 194 provided with an intermediately disposed hingelike portion 196. A fixed electrical contact 198, which may be secured to base 190 as by a rivet 200, is provided with a curled end tab 202 for connecting thereto end 204 of conductor 142. The somewhat curvilinear blade portion 206 of contact 198 is presented so as to be normally in close proximity to the switch contact 108 carried by the moveable arm 194. The contact 108 may also be provided with a curled end tab 208 for securing thereto end 106 of conductor 104.

Throttle lever 24 has an upward extension 210, formed at the end of lateral arm portion 66, which carries a switch actuating member 212. As shown, the actuator 212 has an elongated slot 214 formed therein which received therethrough a screw 216 threadable engaged as at 218 with the arm extension 210. The purpose of the actuator 212, slot 214 and screw 216 is, of course, to provide a means for adjusting the closure of contacts 108 and 206 relative to some predetermined degree of opening of the throttle valve 16 as indicated by the corresponding movement of throttle lever 24. Accordingly, employing such adjusting means, the switch assembly would be set to close the circuit therethrough whenever the throttle valve 16 has been opened to some predetermined degree as, for example, some degree in excess of the throttle opening determined by the highest step 52 of the fast idle cam 46.

OPERATION OF INVENTION Let it be assumed that the vehicle and engine are operating under normal road conditions. At this time the throttle valve, during vehicle motion, will normally be opened considerably in excess of that determined by the high step 52 of cam 46 therefore causing switch 110 to be closed. Further, since the vehicle is in motion, the transmission selector lever 114 will be in some position other than P or N thereby causing the switch member 94 to be closed against contact 92. At this time it can be seen that the circuit described by source 76, conductors 86, 90, switch 94, conductor 104, throttle switch 110, conductor 142, relay coil 134 and conductor 140 is complete except for the open brake responsive switch 88. Accordingly, there is no current flow through this circuit at this time thereby permitting spring 133 to resiliently hold the relay contact 130 closed against associated contacts and 146.

Accordingly, the electrical circuit from source 76 through conductors 126, 127, primary winding 150 and conductor 158 is completed so as to be pulsatingly controlled by the ignition breaker contact assembly 162 thereby permitting normal operation of the secondary winding 154 and ignition distributor assembly 178.

However, let it now be assumed that the foot throttle control 30 is released so as to permit spring 68 to return the throttle valve 16 toward its nominally closed position but that for some reason the throttle valve 16 becomes stuck at some point and does not return to such a nominally closed position. Further, let it be also assumed that the position at which the throttle becomes stuck is one at which the switch actuator 212 still maintains switch assembly 110 closed.

Now, with the above assumed conditions, if the brake pedal 112 is depressed, switch 88 is moved against contact 84 thereby completing the electrical circuitry and energizing relay coil 134 causing the core 132 and relay contact to move downwardly opening the circuit through associated contacts 120 and 146. This, of course, results in an interruption of current flow to the primary winding of coil assembly 152 and prevents any further generation of a spark discharge at any of the igniters or spark plug assemblies 188. Consequently, the engine is shut down preventing any accident from occurring because of a throttle valve stuck in any relatively opened position greater than a predetermined position which is considered safe.

SECOND EMBODIMENT OF THE INVENTION FIG. 4 fragmentarily illustrates a second embodiment of the invention wherein all elements thereof are the same as shown in FIG. 1 except as specifically noted to the contrary. Further, all elements which are like or similar to those of FIGS. 1, 2 and 3 are identified with like reference numbers.

Referring in greater detail to FIG. 4, it can be seen that con duit and passage means 220 and 222 are provided as to communicate between an engine related source of vacuum, such as the interior of the intake manifold 18, and chamber 224 of a pressure responsive switch assembly 226.

As shown, the switch assembly 226 may be comprised generally of housing sections 228 and 230 which peripherally retain a pressure-responsive diaphragm 232 therebetween so as to define two variable but distinct chambers 224 and 234 of which chamber 234 may be vented to the atmosphere as at 236. A bridginglike contact 238 is carried by diaphragm 232 so as to be urged against terminal contacts 240 and 242 by spring 244 whenever the value of the vacuum within chamber 224 has been sufficiently reduced. As can be seen, contacts 240 and 242 are electrically isolated from housing 230 with terminal contact 242 now being connected to end 106 of conductor 104 while a second conductor 246, connected at its end 248 to tab 208 of contact 108, is connected to terminal 240. As previously, stated the remainder of the circuitry is as disclosed in FIG. 1.

Accordingly, it can be seen that the arrangement of FIG. 4 presents means sensitive to another parameter of engine and vehicle operation for completing the control circuitry. That is, even if all of the switches 84, 94 and 110 are closed, the relay coil 134 will still not be energized until such time as terminal contacts 240 and 242 are closed by the bridging contact 238 of switch assembly 226. This would be most beneficial where, for example, the vehicle was experiencing rapid deceleration with the brake being applied but the throttle valve being manually maintained partly open sufficient to close switch 110. At this time the deceleration would generate sufficient manifold vacuum to keep bridging contact 238 away from terminal contacts 240 and 242 and enable the continued normal operation of the ignition system. However, as the vehicle speed, during such deceleration, finally reached a predetermined speed, with the throttle valve still either held or stuck in such partly open position, the manifold vacuum would decrease sufficiently to permit spring 244 to move contact 238 against terminals 240 and 242 thereby closing the circuit through relay coil 134 and discontinuing the normal operation ofthe ignition system.

THIRD EMBODIMENT OF THE INVENTION FIG. 5 illustrates a third embodiment of the invention. All elements which are like or similar to those of the preceding Figures are identified with the reference numbers.

In FIG. 5 it can be seen that the manually actuated conventional ignition switch (often key operated) 118 is connected to terminal 148 of primary coil 150 by a conductor 250. The other terminal 156 of primary coil 150 is also connected to serially situated throttle switch means 110, transmission switch member 94 and brake-responsive switch member 88 which may be electrically connected by conductors 252, 254, 256 and 258 finally leading to ground 80.

The various switches in the arrangement of FIG. 5 operate and function in the same manner as described with reference to FIG. 1; however, the main difference is that with the arrangement of FIG. 5, the employment of the relay assembly 128 and related switch contact 130 is no longer necessary. That is, when conditions are such as to close all of switches 88, 94 and 108, terminal 156 of primary winding 150 is brought directly to ground 80 thereby establishing a current flow of substantially constant value through the primary winding 150. By so establishing the constant value of current flow, there is no induced voltage created in the secondary winding 154 and accordingly no spark discharge can occur at the engine igniter or spark plug assemblies 188.

FOURTH EMBODIMENT OF THE INVENTION FIG. 6 illustrates a fourth embodiment of the invention; all elements which are like or similar to those of FIG. 5 or the preceding Figures are identified with like reference numbers.

In comparing the embodiments of FIGS. 5 and 6 it can be seen that the basic difference therebetween resides in the provision of the pressure responsive switch assembly 226 (disclosed in detail in FIG. 4 in series circuit with switches I10, 94 and 88. As such, the vacuum switch assembly 226 may be electrically connected to terminal I56 of primary winding I50 as by conductor 252 and connected to switch assembly as by a conductor 253. The operation of the embodiment of FIG. 6 is generally the same as that of FIG. 5; that is, when conditions are such as to close all of switches 88, 94, 108 and 238 terminal 156 of primary winding is brought directly to ground 80 thereby establishing a continuing current flow of substantially constant value through the primary winding I50 occurring at the engine igniter or spark plug assemblies 188.

FIFTH EMBODIMENT OF THE INVENTION FIG. 7 illustrates a fifth embodiment of the invention; all elements which are like or similar to those of FIGS. 5 and 6 or any of the preceding Figures are identified with like reference numbers.

In comparing, for example, the embodiments of FIGS. 7 and 5 it can be seen that the basic difference therebetween resides in the provision of an additional switch assembly 260 which is responsive to the speed of the associated vehicle. Such vehicle road speed switch assemblies are well known in the art and therefore it is deemed sufficient to diagrammatically illustrate such speed-responsive switch assembly 260. As illustrated, switch assembly 260 is arranged to be serially effective with the remaining switches 108, 94 and 88.

As is well known, vehicle-speed-responsive switches, such as 260, may be operatively connected to the output shaft of the vehicular main power transmission assembly I17 much in the same manner as are the conventional vehicular speedometer assemblies. It is also conceivable that, with automatic type of transmission assemblies, pressure actuated switches could be employed which are sensitive to hydraulic pressures developed within the transmission assembly which are reflective of vehicular speed.

In any event, in the preferred form of the embodiment of FIG. 7, the vehicle-speed-responsive switch assembly 260 could be set so as to have the switch member 262 thereof close against contact 264 whenever the vehicular speed was sensed to be equal to or greater than a predetermined vehicular speed such as, for example 15.0 miles per hour.

The provision of such a speed-responsive switch assembly 260 overcomes another possible problem that being, for example, accommodating those vehicle operators-which have a habit of riding the brake during normal operation of the vehicle. That is, certain persons keep their left foot constantly on the vehicular brake pedal even when conditions do not require application of the brake; such individuals would than experience a continual stopping and starting of the ignition system as previously described. This could become a problem during slow speed vehicle operation as might occur, for example, in slowly turning a corner at a street intersection when often the vehicle operator has one foot on the throttle pedal 30, causing the throttle valve 16 to be partly opened, and the other foot on the vehicle brake pedal 112 anticipating the possible presence of a pedestrian crossing the street at the corner being turned.

Further, similar brake and throttle positions might occur at, for example, railroad grade crossings where the vehicle might be standing on an incline and waiting for the train to pass. In anticipation of such train passing the operator may well partly depress the throttle foot pedal 30 while also depressing the brake pedal 112 to prevent vehicular motion backwards.

Accordingly, in situations as above, the provision of the vehicle-speed-responsive switch assembly 260 would, because it is open at vehicle speeds below a predetermined minimum value, prevent the termination of the normal functioning of the vehicle ignition system.

In view of the preceding, it should be apparent that various modifications of the various embodiments are possible. For example, if desired, the road or vehicle speed switch assembly 260 could be employed in either of the embodiments of FIGS. 1 or 4 merely by placing it in series with the other parometer control switches 88, 94 and 110; similarly such a speedresponsive switch assembly 260 could be employed in the embodiment of FIG. 6 merely by placing it in series, for example, between the vacuum-responsive switch assembly 226 and terminal 156.

Further, for purposes of clarity, the invention has been disclosed with reference to a carburetor assembly; however, the invention is not so limited to such a combination. That is, the principle purpose of describing the carburetor 10 was to illustrate some air induction passage means with an associated throttle valve for supplying combustion air to an internal combustion engine. Therefore, it should be apparent that the invention can be employed in any induction system having induction passage means whether such be, for example, a carburetor or a fuel injection system. Also, the invention is generally applicable to diesel engines to shut the engine down in the event of a stuck fuel control member, in that event, since there is no ignition system, shutdown would be by a solenoid cutting off air or fuel supply.

Although only a select number of embodiments and modifications of the invention have been disclosed and described, it is apparent that other embodiments and modifications of the invention are possible. within the scope of the appended claims.

I claim:

1. A safety device for a vehicle having an internal combustion engine with air induction passage means provided with a variably openable throttle valve within said induction passage means for variably controlling the admission of air to said engine in accordance with the degree of opening of said throttle valve, said safety device comprising a source of electrical potential, a first switch means closed in response to the movement of a vehicular brake pedal in the brake-applying direction, a second switch means closed in response to the placement of a main power transmission assembly of said vehicle into a condition for transmitting power from said engine to associated drive wheels of said vehicle, third switch means closed in response to said throttle valve being opened a predetermined degree, and electrical conductor means placing said source of electrical potential and said first, second and third switch means in circuit, said first, second and third switch means being effective upon being collectively electrically closed to prevent the occurrence of a spark discharge in a spark plug of said engine.

2. A safety device according to claim 1, wherein said electrical conductor means said source of electrical potential and said first, second and third switch means are arranged so as to be in series circuit relationship with each other.

3. A safety device according to claim 1, including fourth switch means responsive to the collective closure of all of said first, second and third switch means and thereupon effective for preventing said occurrence of said spark discharge.

4. A safety device according to claim 3, wherein said fourth switch means comprises a relay operated electrical switch member situated in a circuit leading from said source of electrical potential to the primary winding of an associated engine ignition system, said electrical switch member being normally closed but being opened by said relay upon the occurrence of the simultaneous closure of said first, second and third switch means.

5. A safety device according to claim 4, wherein said relay comprises an actuating coil electrically energized upon the simultaneous closure of said first, second and third switch means.

6. A safety device according to claim 4, wherein said electrical conductor means said source of electrical potential and said first, second and third switch means are arranged so as to be in series circuit relationship with each other, and wherein said relay comprises an actuating coil electrically connected as to be in said series circuit relationship, said actuating coil being energized to open said electrical switch member upon the simultaneous closure of said first, second and third switch means.

7. A safety device according to claim Lincluding fourth switch means, said fourth switch means being responsive to vacuum generated by said engine and being in said circuit with said electrical conductor means and said first, second and third switch means, and wherein said first, second and third switch means are effective upon being collectively electrically closed to prevent said occurrence of said spark discharge only when said fourth switch means is also electrically closed in response to the generation of said vacuum of a value less than a predetermined value of vacuum.

8. A safety device according to claim 1, including fourth switch means, said fourth switch means being responsive to the speed of said vehicle so as to be closed only after said vehicle has attained a predetermined vehicle speed, said fourth switch means being in said circuit with said electrical conductor means and said first, second and third switch means, and wherein said first, second and third switch means are effective upon being collectively electrically closed to prevent said occurrence of said spark discharge only when said fourth switch means is also electrically closed.

9. A safety device according to claim 1, wherein said circuit also comprises the primary winding of an ignition coil assembly of an associated engine ignition system, wherein one end of said primary winding is electrically connected to one electrical side of said source of electrical potential, and wherein the other end of said primary winding is electrically connected in series circuit relationship to said first, second and third switch means leading to the other electrical side of said source of electrical potential.

10. A safety device according to claim 9, including fourth switch means responsive to engine-generated vacuum, said fourth switch means being connected in series circuit with said first, second and third switch means generally between said other end of said primary winding and said other electrical side of said source of electrical potential, and wherein said first, second and third switch means are effective upon being collectively closed to prevent said occurrence of said spark discharge only when said fourth switch means is also electrically closed in response to the generation of said vacuum of a value less than a predetermined value of vacuum.

11. A safety device according to claim 9, including fourth switch means responsive to the speed of said vehicle so as to be closed only after said vehicle has attained a predetermined vehicle speed, said fourth switch means being connected in series circuit with said first, second and third switch means generally between said other end of said primary winding and said other electrical side of said source of electrical potential, and wherein said first, second and third switch means are effective upon being collectively electrically closed to prevent said occurrence of said spark discharge only when said fourth switch means is also electrically closed.

12. A safety device for a vehicle having an internal combustion engine with air induction passage means provided with a variably openable throttle valve within said induction passage means for variably controlling the admission of air to said engine in accordance with the degree of opening of said throttle valve, an ignition system and a source of electrical potential for energizing said ignition system, said safety device comprising at least a first switch means closed in response to the movement of a vehicular brake pedal in the brake-applying direction, second switch means responsive to the speed of said vehicle so as to be closed only after said vehicle has attained a predetermined vehicle speed and third switch means closed in response to said throttle valve being opened a predetermined degree, and electrical conductor means placing said source of electrical potential and said first, second and third switches, whereby when said switches are all electrically closed said primary coil is grounded out to prevent the occurrence of said spark discharge.

14. A safety device according to claim 12, wherein said electrical conductor means said source of electrical potential and said first, second and third switch means are arranged so as to be in series circuit relationship with each other. 

1. A safety device for a vehicle having an internal combustion engine with air induction passage means provided with a variably openable throttle valve within said induction passage means for variably controlling the admission of air to said engine in accordance with the degree of opening of said throttle valve, saiD safety device comprising a source of electrical potential, a first switch means closed in response to the movement of a vehicular brake pedal in the brake-applying direction, a second switch means closed in response to the placement of a main power transmission assembly of said vehicle into a condition for transmitting power from said engine to associated drive wheels of said vehicle, third switch means closed in response to said throttle valve being opened a predetermined degree, and electrical conductor means placing said source of electrical potential and said first, second and third switch means in circuit, said first, second and third switch means being effective upon being collectively electrically closed to prevent the occurrence of a spark discharge in a spark plug of said engine.
 2. A safety device according to claim 1, wherein said electrical conductor means said source of electrical potential and said first, second and third switch means are arranged so as to be in series circuit relationship with each other.
 3. A safety device according to claim 1, including fourth switch means responsive to the collective closure of all of said first, second and third switch means and thereupon effective for preventing said occurrence of said spark discharge.
 4. A safety device according to claim 3, wherein said fourth switch means comprises a relay operated electrical switch member situated in a circuit leading from said source of electrical potential to the primary winding of an associated engine ignition system, said electrical switch member being normally closed but being opened by said relay upon the occurrence of the simultaneous closure of said first, second and third switch means.
 5. A safety device according to claim 4, wherein said relay comprises an actuating coil electrically energized upon the simultaneous closure of said first, second and third switch means.
 6. A safety device according to claim 4, wherein said electrical conductor means said source of electrical potential and said first, second and third switch means are arranged so as to be in series circuit relationship with each other, and wherein said relay comprises an actuating coil electrically connected as to be in said series circuit relationship, said actuating coil being energized to open said electrical switch member upon the simultaneous closure of said first, second and third switch means.
 7. A safety device according to claim 1, including fourth switch means, said fourth switch means being responsive to vacuum generated by said engine and being in said circuit with said electrical conductor means and said first, second and third switch means, and wherein said first, second and third switch means are effective upon being collectively electrically closed to prevent said occurrence of said spark discharge only when said fourth switch means is also electrically closed in response to the generation of said vacuum of a value less than a predetermined value of vacuum.
 8. A safety device according to claim 1, including fourth switch means, said fourth switch means being responsive to the speed of said vehicle so as to be closed only after said vehicle has attained a predetermined vehicle speed, said fourth switch means being in said circuit with said electrical conductor means and said first, second and third switch means, and wherein said first, second and third switch means are effective upon being collectively electrically closed to prevent said occurrence of said spark discharge only when said fourth switch means is also electrically closed.
 9. A safety device according to claim 1, wherein said circuit also comprises the primary winding of an ignition coil assembly of an associated engine ignition system, wherein one end of said primary winding is electrically connected to one electrical side of said source of electrical potential, and wherein the other end of said primary winding is electrically connected in series circuit relationship to saiD first, second and third switch means leading to the other electrical side of said source of electrical potential.
 10. A safety device according to claim 9, including fourth switch means responsive to engine-generated vacuum, said fourth switch means being connected in series circuit with said first, second and third switch means generally between said other end of said primary winding and said other electrical side of said source of electrical potential, and wherein said first, second and third switch means are effective upon being collectively closed to prevent said occurrence of said spark discharge only when said fourth switch means is also electrically closed in response to the generation of said vacuum of a value less than a predetermined value of vacuum.
 11. A safety device according to claim 9, including fourth switch means responsive to the speed of said vehicle so as to be closed only after said vehicle has attained a predetermined vehicle speed, said fourth switch means being connected in series circuit with said first, second and third switch means generally between said other end of said primary winding and said other electrical side of said source of electrical potential, and wherein said first, second and third switch means are effective upon being collectively electrically closed to prevent said occurrence of said spark discharge only when said fourth switch means is also electrically closed.
 12. A safety device for a vehicle having an internal combustion engine with air induction passage means provided with a variably openable throttle valve within said induction passage means for variably controlling the admission of air to said engine in accordance with the degree of opening of said throttle valve, an ignition system and a source of electrical potential for energizing said ignition system, said safety device comprising at least a first switch means closed in response to the movement of a vehicular brake pedal in the brake-applying direction, second switch means responsive to the speed of said vehicle so as to be closed only after said vehicle has attained a predetermined vehicle speed and third switch means closed in response to said throttle valve being opened a predetermined degree, and electrical conductor means placing said source of electrical potential and said first, second and third switch means in circuit, said first, second and third switch means being effective upon being collectively electrically closed to prevent the occurrence of a spark discharge in a spark plug of said engine.
 13. A safety device according to claim 12, wherein said ignition system additionally includes a coil having primary and secondary windings, said device including a ground connection for said primary winding through said first, second and third switches, whereby when said switches are all electrically closed said primary coil is grounded out to prevent the occurrence of said spark discharge.
 14. A safety device according to claim 12, wherein said electrical conductor means said source of electrical potential and said first, second and third switch means are arranged so as to be in series circuit relationship with each other. 